Abstract: According to research on thermodynamic calculation and experiment of carbon dioxide and oxygen mixed injection (COMI) steelmaking process, material and energy equilibrium models of converter steelmaking with all hot metal by COMI process were established. The results show that COMI process is significant for converter steelmaking with all hot metal. It can not only overcome the problems of a large amount of slag and big splashing in a conventional converter, but also can improve the calorific value of converter gas, reduce the oxygen consumption per ton steel, lower the consumption of lime, and accommodate the amount of iron ore.